The Sig Sauer P229 E2 9mm and Sig P229 made from late December 2010 now has a wider magwell which is the same as the Sig Sauer P229 .40/.357.  This is the correct magazine for those pistols, you need to use the Sig Sauer P229-1 magazine. If you have the earlier P228 or P229 9mm, Sig P229 Classic Carry or Sig P229 Legacy with the narrow magazine (came standard with a 13 round magazine) these magazines have too wide of a magazine tube, they won't fit. 

Compatible Firearms: SIG SAUER P229-1

Caliber: 9mm

Capacity: 17 rounds

Coating: Anti-Friction

Follower: High-impact polymer

Tube: Heat treated carbon steel

Spring: High tensile music wire

Floorplate: High-impact polymer +2 floorplate

SKU: MGP22917AFC — UPC: 765595520158

• Anti-Friction coating allows for easy loading, reduced malfunctions, and superior anti-corrosion properties
  
  Constructed from certified carbon steel and features a heat treated housing and high-impact polymer or certified carbon steel follower and floorplate. The magazine spring is made of high strength type "D" music wire-the strongest wire available. TIG welding provides additional strength and a seamless finish. Each magazine surface is specially treated to ensure high corrosion resistance.

Mec-Gar is proud to be the Original Equipment Manufacturer of magazines to most of the prominent firearm manufacturers for the last 40 years including AMT - Armscor - Astra - Beretta Bernadelli - FN Browning - BUL - Charles Daly - Colt - CZ - IMI - Kel-Tec - Kimber - Llama - North American Arms - Remington - Sigarms - Smith & Wesson - Springfield Armory - STI - Standard Arms - Star - Steyr - Tanfoglio - Taurus - Walther